Relax NG compact syntax and entities

Hi,
I'm new to Relax NG and I'm trying to write a grammar form my application.
Because I need to use the same element names across multiple xml files,
I created several entities in an external file (commands.ent) that I include 
in the Relax NG grammar as follows:

<!DOCTYPE grammar[
    <!ENTITY % commands SYSTEM "../commands.ent">
    %commands;
]>
<grammar .........>
 ........
</grammar>

Is there a way of doing the same with the compact syntax?

Thanks

Alessandro